Lincoln Electric IM703-A User manual

Brand: Lincoln Electric

Model: IM703-A

Category: Welding System

Type: User manual

This manual is also suitable for

PRECISION TIG 375

PRECISION TIG 375

OPERATOR’S MANUAL

IM703-A

November, 2004

Safety Depends on You

Lincoln arc welding and cutting

equipment is designed and built

with safety in mind. However, your

overall safety can be increased by

proper installation ... and thoughtful

operation on your part. DO NOT

INSTALL, OPERATE OR REPAIR

THIS EQUIPMENT WITHOUT

READING THIS MANUAL AND

THE SAFETY PRECAUTIONS

CONTAINED THROUGHOUT.

And, most importantly, think before

you act and be careful.

For use with machines having Code Numbers:

10809; 10810; 10894

• Sales and Service through Subsidiaries and Distributors Worldwide •

Cleveland, Ohio 44117-1199 U.S.A. TEL: 216.481.8100 FAX: 216.486.1751 WEB SITE: www.lincolnelectric.com

• World's Leader in Welding and Cutting Products •

Precision TIG 375 Welding

Package shown with optional

Advanced Control Panel

IP21S

This manual covers equipment which is no

longer in production by The Lincoln Electric Co.

Specications and availability of optional

features may have changed.

FOR ENGINE

powered equipment.

1.a. Turn the engine off before troubleshooting and maintenance

work unless the maintenance work requires it to be running.

____________________________________________________

1.b.Operate engines in open, well-ventilated

areas or vent the engine exhaust fumes

outdoors.

____________________________________________________

1.c. Do not add the fuel near an open flame weld-

ing arc or when the engine is running. Stop

the engine and allow it to cool before refuel-

ing to prevent spilled fuel from vaporizing on

contact with hot engine parts and igniting. Do

not spill fuel when filling tank. If fuel is spilled,

wipe it up and do not start engine until fumes

have been eliminated.

____________________________________________________

1.d. Keep all equipment safety guards, covers and devices in posi-

tion and in good repair.Keep hands, hair, clothing and tools

away from V-belts, gears, fans and all other moving parts

when starting, operating or repairing equipment.

____________________________________________________

1.e. In some cases it may be necessary to remove safety

guards to perform required maintenance. Remove

guards only when necessary and replace them when the

maintenance requiring their removal is complete.

Always use the greatest care when working near moving

parts.

___________________________________________________

1.f. Do not put your hands near the engine fan.

Do not attempt to override the governor or

idler by pushing on the throttle control rods

while the engine is running.

___________________________________________________

1.g. To prevent accidentally starting gasoline engines while

turning the engine or welding generator during maintenance

work, disconnect the spark plug wires, distributor cap or

magneto wire as appropriate.

SAFETY

ARC WELDING CAN BE HAZARDOUS. PROTECT YOURSELF AND OTHERS FROM POSSIBLE SERIOUS INJURY OR DEATH.

KEEP CHILDREN AWAY. PACEMAKER WEARERS SHOULD CONSULT WITH THEIR DOCTOR BEFORE OPERATING.

Read and understand the following safety highlights. For additional safety information, it is strongly recommended that you

purchase a copy of “Safety in Welding & Cutting - ANSI Standard Z49.1” from the American Welding Society, P.O. Box 351040,

Miami, Florida 33135 or CSA Standard W117.2-1974. A Free copy of “Arc Welding Safety” booklet E205 is available from the

Lincoln Electric Company, 22801 St. Clair Avenue, Cleveland, Ohio 44117-1199.

BE SURE THAT ALL INSTALLATION, OPERATION, MAINTENANCE AND REPAIR PROCEDURES ARE

PERFORMED ONLY BY QUALIFIED INDIVIDUALS.

WARNING

Mar ‘95

ELECTRIC AND

MAGNETIC FIELDS

may be dangerous

2.a. Electric current flowing through any conductor causes

localized Electric and Magnetic Fields (EMF). Welding

current creates EMF fields around welding cables and

welding machines

2.b. EMF fields may interfere with some pacemakers, and

welders having a pacemaker should consult their physician

before welding.

2.c. Exposure to EMF fields in welding may have other health

effects which are now not known.

2.d. All welders should use the following procedures in order to

minimize exposure to EMF fields from the welding circuit:

2.d.1.

Route the electrode and work cables together - Secure

them with tape when possible.

2.d.2. Never coil the electrode lead around your body.

2.d.3. Do not place your body between the electrode and

work cables. If the electrode cable is on your right

side, the work cable should also be on your right side.

2.d.4. Connect the work cable to the workpiece as close as

possible to the area being welded.

2.d.5. Do not work next to welding power source.

1.h. To avoid scalding, do not remove the

radiator pressure cap when the engine is

hot.

For Diesel Engines: Diesel engine exhaust and

some of its constituents are known to the State

of California to cause cancer, birth defects, and

other reproductive harm.

For Gasoline Engines: The engine exhaust from

this product contains chemicals known to the

State of California to cause cancer, birth defects,

or other reproductive harm.

CALIFORNIA PROPOSITION 65 WARNINGS

SAFETY

ARC RAYS can burn.

4.a. Use a shield with the proper filter and cover

plates to protect your eyes from sparks and

the rays of the arc when welding or observing

open arc welding. Headshield and filter lens

should conform to ANSI Z87. I standards.

4.b. Use suitable clothing made from durable flame-resistant

material to protect your skin and that of your helpers from

the arc rays.

4.c. Protect other nearby personnel with suitable, non-flammable

screening and/or warn them not to watch the arc nor expose

themselves to the arc rays or to hot spatter or metal.

ELECTRIC SHOCK can kill.

3.a. The electrode and work (or ground) circuits

are electrically “hot” when the welder is on.

Do not touch these “hot” parts with your bare

skin or wet clothing. Wear dry, hole-free

gloves to insulate hands.

3.b. Insulate yourself from work and ground using dry insulation.

Make certain the insulation is large enough to cover your full

area of physical contact with work and ground.

In addition to the normal safety precautions, if welding

must be performed under electrically hazardous

conditions (in damp locations or while wearing wet

clothing; on metal structures such as floors, gratings or

scaffolds; when in cramped positions such as sitting,

kneeling or lying, if there is a high risk of unavoidable or

accidental contact with the workpiece or ground) use

the following equipment:

• Semiautomatic DC Constant Voltage (Wire) Welder.

• DC Manual (Stick) Welder.

• AC Welder with Reduced Voltage Control.

3.c. In semiautomatic or automatic wire welding, the electrode,

electrode reel, welding head, nozzle or semiautomatic

welding gun are also electrically “hot”.

3.d. Always be sure the work cable makes a good electrical

connection with the metal being welded. The connection

should be as close as possible to the area being welded.

3.e. Ground the work or metal to be welded to a good electrical

(earth) ground.

3.f.

Maintain the electrode holder, work clamp, welding cable and

welding machine in good, safe operating condition. Replace

damaged insulation.

3.g. Never dip the electrode in water for cooling.

3.h. Never simultaneously touch electrically “hot” parts of

electrode holders connected to two welders because voltage

between the two can be the total of the open circuit voltage

of both welders.

3.i. When working above floor level, use a safety belt to protect

yourself from a fall should you get a shock.

3.j. Also see Items 6.c. and 8.

FUMES AND GASES

can be dangerous.

5.a. Welding may produce fumes and gases

hazardous to health. Avoid breathing these

fumes and gases.When welding, keep

your head out of the fume. Use enough

ventilation and/or exhaust at the arc to keep

fumes and gases away from the breathing zone. When

welding with electrodes which require special

ventilation such as stainless or hard facing (see

instructions on container or MSDS) or on lead or

cadmium plated steel and other metals or coatings

which produce highly toxic fumes, keep exposure as

low as possible and below Threshold Limit Values (TLV)

using local exhaust or mechanical ventilation. In

confined spaces or in some circumstances, outdoors, a

respirator may be required. Additional precautions are

also required when welding on galvanized steel.

5.b.

Do not weld in locations near chlorinated hydrocarbon

vapors

coming from degreasing, cleaning or spraying operations.

The heat and rays of the arc can react with solvent vapors

form phosgene, a highly toxic gas, and other irritating

products.

5.c. Shielding gases used for arc welding can displace air and

cause injury or death. Always use enough ventilation,

especially in confined areas, to insure breathing air is safe.

5.d. Read and understand the manufacturer’s instructions for this

equipment and the consumables to be used, including the

material safety data sheet (MSDS) and follow your

employer’s safety practices. MSDS forms are available from

your welding distributor or from the manufacturer.

5.e. Also see item 1.b.

Mar ‘95

FOR ELECTRICALLY

powered equipment.

8.a. Turn off input power using the disconnect

switch at the fuse box before working on

the equipment.

8.b. Install equipment in accordance with the U.S. National

Electrical Code, all local codes and the manufacturer’s

recommendations.

8.c. Ground the equipment in accordance with the U.S. National

Electrical Code and the manufacturer’s recommendations.

CYLINDER may explode

if damaged.

7.a. Use only compressed gas cylinders

containing the correct shielding gas for the

process used and properly operating

regulators designed for the gas and

pressure used. All hoses, fittings, etc. should be suitable for

the application and maintained in good condition.

7.b. Always keep cylinders in an upright position securely

chained to an undercarriage or fixed support.

7.c. Cylinders should be located:

• Away from areas where they may be struck or subjected to

physical damage.

• A safe distance from arc welding or cutting operations and

any other source of heat, sparks, or flame.

7.d. Never allow the electrode, electrode holder or any other

electrically “hot” parts to touch a cylinder.

7.e. Keep your head and face away from the cylinder valve outlet

when opening the cylinder valve.

7.f. Valve protection caps should always be in place and hand

tight except when the cylinder is in use or connected for

use.

7.g. Read and follow the instructions on compressed gas

cylinders, associated equipment, and CGA publication P-l,

“Precautions for Safe Handling of Compressed Gases in

Cylinders,” available from the Compressed Gas Association

1235 Jefferson Davis Highway, Arlington, VA 22202.

iii

SAFETY

iii

Mar ‘95

WELDING SPARKS can

cause fire or explosion.

6.a.

Remove fire hazards from the welding area.

If this is not possible, cover them to prevent

the welding sparks from starting a fire.

Remember that welding sparks and hot

materials from welding can easily go through small cracks

and openings to adjacent areas. Avoid welding near

hydraulic lines. Have a fire extinguisher readily available.

6.b. Where compressed gases are to be used at the job site,

special precautions should be used to prevent hazardous

situations. Refer to “Safety in Welding and Cutting” (ANSI

Standard Z49.1) and the operating information for the

equipment being used.

6.c. When not welding, make certain no part of the electrode

circuit is touching the work or ground. Accidental contact can

cause overheating and create a fire hazard.

6.d. Do not heat, cut or weld tanks, drums or containers until the

proper steps have been taken to insure that such procedures

will not cause flammable or toxic vapors from substances

inside. They can cause an explosion even

though

they have

been “cleaned”. For information, purchase “Recommended

Safe Practices for the

Preparation

for Welding and Cutting of

Containers and Piping That Have Held Hazardous

Substances”, AWS F4.1 from the American Welding Society

(see address above).

6.e. Vent hollow castings or containers before heating, cutting or

welding. They may explode.

6.f.

Sparks and spatter are thrown from the welding arc. Wear oil

free protective garments such as leather gloves, heavy shirt,

cuffless trousers, high shoes and a cap over your hair. Wear

ear plugs when welding out of position or in confined places.

Always wear safety glasses with side shields when in a

welding area.

6.g. Connect the work cable to the work as close to the welding

area as practical. Work cables connected to the building

framework or other locations away from the welding area

increase the possibility of the welding current passing

through lifting chains, crane cables or other alternate circuits.

This can create fire hazards or overheat lifting chains or

cables until they fail.

6.h. Also see item 1.c.

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Thank You

for selecting a QUALITY product by Lincoln Electric. We want you

to take pride in operating this Lincoln Electric Company product •••

as much pride as we have in bringing this product to you!

Read this Operators Manual completely before attempting to use this equipment. Save this manual and keep it

handy for quick reference. Pay particular attention to the safety instructions we have provided for your protection.

The level of seriousness to be applied to each is explained below:

WARNING

This statement appears where the information must be followed exactly to avoid serious personal injury or

loss of life.

This statement appears where the information must be followed to avoid minor personal injury or damage to

this equipment.

CAUTION

Please Examine Carton and Equipment For Damage Immediately

When this equipment is shipped, title passes to the purchaser upon receipt by the carrier. Consequently, Claims

for material damaged in shipment must be made by the purchaser against the transportation company at the time

the shipment is received.

Please record your equipment identification information below for future reference. This information can be found

on your machine nameplate.

Product _________________________________________________________________________________

Model Number ___________________________________________________________________________

Code Number or Date Code_________________________________________________________________

Serial Number____________________________________________________________________________

Date Purchased___________________________________________________________________________

Where Purchased_________________________________________________________________________

Whenever you request replacement parts or information on this equipment, always supply the information you

have recorded above. The code number is especially important when identifying the correct replacement parts.

On-Line Product Registration

- Register your machine with Lincoln Electric either via fax or over the Internet.

• For faxing: Complete the form on the back of the warranty statement included in the literature packet

accompanying this machine and fax the form per the instructions printed on it.

• For On-Line Registration: Go to our

WEB SITE at www.lincolnelectric.com. Choose “Quick Links” and then

“Product Registration”. Please complete the form and submit your registration.

TABLE OF CONTENTS

Page.

Installation ..........................................................................................................Section A

Technical Specifications ........................................................................................A-1,A-2

Safety Precautions

.. ............................................................................................................................................... .A-3

Select Suitable Location........................................................................................A-3

Grinding .................................................................................................................A-3

Stacking.................................................................................................................A-3

Undercarriage Lifting and Moving .........................................................................A-3

Tilting .....................................................................................................................A-3

Environmental Rating ............................................................................................A-3

Machine Grounding and High F

REQUENCY INTERFERENCE PROTECTION ...................A-3,A-4

Input and Grounding Connections ..............................................................................A-4

Output Cable, Connections and Limitations ................................................................A-5

Work Cable Connection ..................................................................................A-5

Stick Electrode Cable Connection ..................................................................A-5

TIG Torch Connection .....................................................................................A-6

Auxiliary Power Connections ..........................................................................A-7

Remote Control (If Used) ................................................................................A-7

Robotic Interface Connection ..................................................................A-7, A-8

________________________________________________________________________

PERATION .........................................................................................................................................................Section B-1

Safety Precautions.......................................................................................................B-1

Product Description......................................................................................................B-1

Pipe Thawing.........................................................................................................B-1

Duty Cycle: ............................................................................................................B-1

Recommended Processes and Equipment ...........................................................B-2

Controls and Settings ..........................................................................B-3 THRU B-6

Internal Set Up Controls ........................................................................................B-7

Sick Welding Features...........................................................................................B-7

TIG Welding Features ...........................................................................................B-7

2 Step Trigger Modes......................................................................................B-8

4 Step Trigger Modes ....................................................................................B-9

TIG Welding Cycle Chart ....................................................................................B-10

Setup Guidelines for TIG Welding with an Amptrol.....................................B-10, B11

Making a TIG Weld with an Amptrol....................................................................B-12

________________________________________________________________________

Accessories

............................................................................................................................................... .......Section C

Optional Equipment .....................................................................................................C-1

________________________________________________________________________

Maintenance

......................................................................................................................................................Section D

Safety Precautions.......................................................................................................D-1

Routine and Periodic Maintenance..............................................................................D-1

Overload Protection .....................................................................................................D-1

Service Procedures, Component Access,Spark Gap Adjustment ...............................D-2

Under-Cooler Service ..................................................................................................D-2

________________________________________________________________________

Troubleshooting

.............................................................................................................................................Section E

Safety Precautions.......................................................................................................E-1

How To Use TroubleShooting Guide............................................................................E-1

Troubleshooting.................................................................................................E-2 to E-7

________________________________________________________________________

Diagrams

..............................................................................................................................................................Section F

Wiring Diagrams..............................................................................................................................................F-1, F-2

Dimension Prints.............................................................................................................................................F-3, F-4

________________________________________________________________________

Parts List

........................................................................................................................................................................P404

vivi

A-1

INSTALLATION

PRECISION TIG 375

A-1

TECHNICAL SPECIFICATIONS-

PRECISION TIG 375 (K1903-1 Domestic Package*-60Hz)

(K1833-1 Domestic,K1833-2 Canadian-60Hz) (K1834-1 Export-50/60Hz)

Voltage + 10%

208/230/460

230/460/575

220-230/

380-400/415

Max. Amps With Power Factor Capacitor

112/102/51

139/126/63

102/92/46

128/116/58

80/72/36

104/92/47

68/62/31

102/51/41

125/63/50

92/46/37

116/58/46

72/36/29

94/47/38

62/31/25

.86 min.

1.0KW

119/69/63

118/68/62

110/64/59

97/56/52

88/51/47

73/42/39

48/28/25

.67 min.

.8KW

Duty Cycle-Applications

40%

AC/DC Stick / Balance TIG

Unbalance (70% Penetration

) AC TIG

60%

AC/DC Stick / Balance TIG

Unbalance (70% Penetration

) AC TIG

100%

AC/DC Stick / Balance TIG

Unbalance (70% Penetration

) AC TIG

Idle Amps

40%

AC/DC Stick / Balance TIG

Unbalance (70% Penetration

) AC TIG

60%

AC/DC Stick / Balance TIG

Unbalance (70% Penetration

) AC TIG

100%

AC/DC Stick / Balance TIG

Unbalance (70% Penetration

) AC TIG

Idle Amps

Rated Power Factor (Stick)

Idle Power

40%

AC/DC Stick / Balance TIG

Unbalance (70% Penetration

) AC TIG

60%

AC/DC Stick / Balance TIG

Unbalance (70% Penetration

) AC TIG

100%

AC/DC Stick / Balance TIG

Unbalance (70% Penetration

) AC TIG

Idle Amps

Rated Power Factor (Stick)

Idle Power

RATED INPUT - SINGLE PHASE ONLY

Number

K1833-1

K1903-1

K1833-2

K1834-1

RATED OUTPUT - NEMA EW1 Class ll (40) K1903-1,K1833-1,K1833-2

Duty Cycle-Applications

40%

AC/DC Stick / Balance TIG

Unbalance (70% Penetration

) AC TIG

60%

AC/DC Stick / Balance TIG

Unbalance (70% Penetration

) AC TIG

100%

AC/DC Stick / Balance TIG

Unbalance (70% Penetration

) AC TIG

Volts at Rated Amperes

35.0

17.2

34.0

16.9

32.0

16.3

Amps

375

350

325

300

275

*Shown on Front of this IM manual with Under-Cooler Cart and Advanced Control Panel (Refer to Optional Equipment)

Exceeds NEMA Unbalanced Load Specification comparable for Auto-Balance.

NRTL/C

IEC 60974-1

N80

K1833-1, -2

K1834-1

K1903-1

A-2

INSTALLATION

PRECISION TIG 375

A-2

ADDITIONAL OUTPUT CAPACITY

Output Current

Range

2Amps DC

420Amps AC-DC

Type of Output

CC (Constant Current)

AC/DC (GTAW)

Stick (SMAW)

Maximum Open

Circuit Voltage

(STICK AND TIG)

AC/DC OCV: 80

Auxiliary Power

K1903-1, K1833-1, K1833-2

15Amp Circuit Breaker and NEMA 5-15R Duplex

Receptacle for up to:

115VAC 8 Amp Auxiliary Power Receptacle

115VAC 5 Amp weld Switched Cooler Receptacle

K1834-1

5 Amp Circuit Breaker

and grounded 220VAC

Euro(Schuko) receptacle

Height Width Depth Weight

31.0 in. 22.0 in. 26.0 in. 507 lbs.

787 mm 559 mm 660 mm 230 kgs.

49.7 in. 28.0 in. 41.0 in. 751 lbs.

1262 mm 711 mm 1041 mm 341 kgs.

PHYSICAL DIMENSIONS

ALSO CALLED ‘INVERSE TIME" OR "THERMAL/MAGNETIC " CIRCUIT BREAKERS; CIRCUIT BREAKERS WHICH HAVE A DELAY IN TRIPPING ACTION THAT DECREASES AS

THE MAGNITUDE OF CURRENT INCREASES.

*50/60HZ IEC Max. range exceeds 310A.

TEMPERATURE RANGES

OPERATING TEMPERATURE RANGE

-20°C to +40°C (-04° to +104°F)

TRANSFORMER INSULATION CLASS 180°C (H)

STORAGE TEMPERATURE RANGE

-40°C to +85°C (-40° to +185°F)

For all Stick, DC TIG, and Balanced AC TIG Welding

at 375A/40% Duty Cycle with out Standard Power

Factor Correction Capacitors

Based on the 1999 U.S. National Electrical Code

For Unbalanced AC TIG Welding Above 275 Amps:

350A/40% Duty Cycle, Auto-Balance Penetration with

out Standard Power Factor Correction Capacitors

Based on the 1999 U.S. National Electrical Code

RECOMMENDED INPUT WIRE AND FUSE SIZES

Input

Voltage /

phase/

Frequency

208/1/60

230/1/60

460/1/60

575/1/60

220-230/1/50/60

380-400/1/50/60

415/1/50/60

Input

Ampere

Rating

Rating on

Nameplate

112

102

119

Input

Ampere

Rating

139

126

118

Type 75°C

Copper

Ground Wire in

Conduit AWG

(IEC) Sizes

6 (13.3 mm

)

6 (13.3 mm

)

8 (8.4 mm

)

10 (5.3mm

)

6 (13.3 mm

)

6 (13.3 mm

)

6 (13.3 mm

)

Type 75°C

Copper

Ground Wire in

Conduit AWG

(IEC) Sizes

6 (13.3 mm

)

6 (13.3 mm

)

8 (8.4 mm

)

8 (8.4 mm

)

6 (13.3 mm

)

6 (13.3 mm

)

6 (13.3 mm

)

Fuse

(Super Lag)

or Breaker

Size

150

110

Fuse

(Super Lag)

or Breaker

Size

200

175

150

110

Type 75°C

Copper Wire in

Conduit AWG

(IEC) Sizes

40°C (104°F)

Ambient

3 (26.7 mm

)

3 (26.7 mm

)

6 (13.3mm

)

8 (8.4 mm

)

3 (26.7 mm

)

4 (21.2 mm

)

4 (21.2 mm

)

Type 75°C

Copper Wire in

Conduit AWG

(IEC) Sizes

40°C (104°F)

Ambient

1 (42.4 mm

)

2 (33.6 mm

)

6 (13.3 mm

)

6 (13.3 mm

)

3 (26.7 mm

)

4 (21.2 mm

)

4 (21.2 mm

)

RATED OUTPUT - IEC 60974-1 (K1834-1)

Duty Cycle-Applications

40%

AC/DC Stick / Balance TIG

Unbalance (70% Penetration

) AC TIG

60%

AC/DC Stick / Balance TIG

Unbalance (70% Penetration

) AC TIG

100%

AC/DC Stick / Balance TIG

Unbalance (70% Penetration

) AC TIG

Volts at Rated Amperes

35.0

24.0

34.0

23.0

32.0

21.0

Amps

375

350

325

300

275

A-3

INSTALLATION

PRECISION TIG 375

A-3

SAFETY PRECAUTIONS

SELECT SUITABLE LOCATION

Place the welder where clean cooling air can freely cir-

culate in through the top rear vents and out through the

bottom rear vents. Dirt, dust or any foreign material

that can be drawn into the welder should be kept at a

minimum. Failure to observe these precautions can

result in excessive operating temperatures and nui-

sance trips.

GRINDING

Do not direct grinding particles towards the welder. An

abundance of conductive material can cause mainte-

nance problems.

STACKING

The Precision TIG 375's cannot be stacked .

UNDERCARRIAGE LIFTING AND MOVING

When the Precision TIG 375 is purchased as a weld-

ing package, or used with any of the available

Undercarriage optional accessories, proper installation

makes the Precision TIG 375 lift bale nonfunctional.

Do not attempt to lift the power source with an under-

carriage attached. The undercarriage is designed for

hand moving only; mechanized movement can lead to

personal injury and/or damage to the Precision TIG

375.

TILTING

Each machine must be placed on a secure, level sur-

face, either directly or on a recommended undercar-

riage. The machine may topple over if this precaution

is not followed.

ENVIRONMENTAL RATING

Precision TIG 375 power sources carry an IP21S

Environmental rating. They are rated for use in damp,

dirty rain-sheltered environments.

MACHINE GROUNDING AND HIGH FRE-

QUENCY INTERFERENCE PROTECTION

The frame of the welder must be grounded. A ground screw

marked with the symbol is located on the input connection

panel (Figure A.1) for this purpose. See your local and nation-

al electrical codes for proper grounding methods.

The spark gap oscillator in the high frequency genera-

tor, being similar to a radio transmitter, can be blamed

for many radio, TV and electronic equipment interfer-

ence problems. These problems may be the result of

radiated interference. Proper grounding methods can

reduce or eliminate radiated interference.

The Precision TIG 375 has been field tested under rec-

ommended installation conditions and has been found

to comply with F.C.C. allowable radiation limits. This

welder has also been found to comply with NEMAstan-

dards for high frequency stabilized power sources.

Radiated interference can develop in the following four

ways:

• Direct interference radiated from the welder.

• Direct interference radiated from the welding leads.

• Direct interference radiated from feedback into the

power lines.

• Interference from re-radiation of "pickup" by

ungrounded metallic objects.

Keeping these contributing factors in mind, installing

the equipment per the following instructions should

minimize problems.

1. Keep the welder power supply lines as short as pos-

sible and completely enclose them in rigid metallic

conduit or equivalent shielding for a minimum dis-

tance of 50 feet (15.2 m). There must be good elec-

trical contact between this conduit and the welder.

Both ends of the conduit must be connected to a

driven ground and the entire length must be contin-

uous.

2. Keep the work and electrode leads as short as pos-

sible and as close together as possible. Lengths

should not exceed 25 feet (7.6 m). Tape the leads

together when practical.

Read entire installation section before starting

installation.

ELECTRIC SHOCK can kill.

• Only qualified personnel should

perform this installation.

• Turn the input power OFF at the

disconnect switch or fuse box

before working on this

equipment.

• Do not touch electrically hot

parts.

• Always connect the Precision TIG 375 grounding screw (behind

the reconnect panel cover located near the back of the left case

side) to a good electrical earth ground.

• Always connect the Precision TIG 375 to a power supply

grounded in accordance with the National Electrical Code and

all local codes.

WARNING

INPUT and GROUNDING CONNECTIONS

Be sure the voltage, phase, and frequency of the input

power is as specified on the rating plate, located on the

rear of the machine.

Remove the reconnect panel cover located near the

back of the left case side to reveal the reconnect panel.

Welder supply line entry provision is in the case rear

panel. Entry is through a 1.75 inch (44 mm) diameter

hole in the case back. Appropriate supply line strain

relief clamp is provided by installer. (See Figure A.1)

All connections should be made in accordance

with all local codes and national electrical codes.

Installation by a qualified electrician is recom-

mended.

1. Connect the terminal marked (below the recon-

nect panel) to an earth ground.

2. Connect the input leads to terminals marked L1 (U)

and L2 (V) on the reconnect panel. Use a single

phase line or one phase of a two or three phase line.

3. On multiple input voltage welders, be sure the

reconnect panel is connected for the voltage being

supplied to the welder.

Failure to follow these instructions can cause

immediate failure of components within the welder.

------------------------------------------------------------------------

A-4

INSTALLATION

PRECISION TIG 375

A-4

3. Be sure the torch and work cable rubber coverings

are free of cuts and cracks that allow high frequen-

cy leakage. Cables with high natural rubber content,

such as Lincoln Stable-Arc® better resist high fre-

quency leakage than neoprene and other synthetic

rubber insulated cables.

4. Keep the torch in good repair and all connections

tight to reduce high frequency leakage.

5. The work terminal must be connected to a ground

within ten feet of the welder, using one of the fol-

lowing methods:

• A metal underground water pipe in direct contact

with the earth for ten feet or more.

• A 3/4" (19 mm) galvanized pipe or a 5/8" (16 mm)

solid galvanized iron, steel or copper rod driven at

least eight feet into the ground.

The ground should be securely made and the ground-

ing cable should be as short as possible using cable of

the same size as the work cable, or larger. Grounding

to the building frame electrical conduit or a long pipe

system can result in re-radiation, effectively making

these members radiating antennas. (This is not rec-

ommended).

6. Keep all access panels and covers securely in

place.

7. All electrical conductors within 50 feet (15.2 m) of

the welder should be enclosed in grounded rigid

metallic conduit or equivalent shielding. Flexible

helically-wrapped metallic conduit is generally not

suitable.

8. When the welder is enclosed in a metal building,

several good earth driven electrical grounds (as in 5

above) around the periphery of the building are rec-

ommended.

Failure to observe these recommended installation

procedures can cause radio or TV interference prob-

lems and result in unsatisfactory welding performance

resulting from lost high frequency power.

WARNING

ELECTRIC SHOCK can kill.

• Turn the input power OFF at the

disconnect switch or fuse box

before working on this

equipment.

FIGURE A.1

CONNECT INPUT

POWER LEADS

CONNECT INPUT

VOLTAGE LEVEL

CONNECT INPUT

GROUND LEAD

CAUTION

A-5

INSTALLATION

PRECISION TIG 375

A-5

Recommended Cable Sizes for Combined Lengths of

Copper Work and Electrode Cables using 75

C Wire:

Machine Rating 0 to 100 Ft. 101 to 200 Ft 201 to 250 Ft

375A/40% #1 (42.4 mm

) 1/0 (53.5 mm

) 2/0 (67.4 mm

)

WORK CABLE CONNECTION

A15’ (2/0) weld cable with clamp is available (K2150-1), or

included with the Precision TIG Welding Package model.

Otherwise, it is user provided.

With power source off, connect a separate work cable

to the 1/2-13 threaded "WORK" stud of the welder, and

secure a tight connection with the flange nut provided.

The work cable should be routed through the cable

strain relief hole provided in the base directly below the

welding output terminal.

Note: If the Precision TIG is equipped with an Under-

Cooler or Under-Storage unit, the coiled work cable

and clamp, or excess work cable length, may be con-

veniently stored in the drawer while remaining con-

nected.

STICK ELECTRODE CABLE CONNECTION

If manual stick welding is desired, with power source

off, connect a stick electrode cable to the 1/2-13

threaded "STICK Electrode" stud of the welder, and

secure a tight connection with the flange nut provided.

The electrode cable should be routed through the

cable strain relief hole provided in the base directly

below the welding output terminal.

DISCONNECT STICK ELECTRODE WELDING

CABLE WHEN TIG WELDING.

EVEN THOUGH HI-FREQ IS NOT APPLIED TO THE

PRECISION TIG STICK TERMINAL, IT WILL BE

ELECTRICALLY "HOT" TO WORK WHEN TIG

WELDING.

------------------------------------------------------------------------

Welders are shipped connected for the highest input

voltage as listed on the rating plate. To change this

connection, designations on the reconnect panel LOW,

MID, and HIGH correspond to the name plated input

voltages of a triple voltage welder. Dual voltage

welders use only LOW and HIGH.

EXAMPLE: On a 208/230/460 volt welder, LOW is

208V, MID is 230V, and HIGH is 460V.

Note: Export model has a voltage range for LOW and

MID connections: LOW is 220-230V, MID is

380-400V and High is 415V.

Reconnect the jumper strap to the terminal stud corre-

sponding to the input voltage level used. Make sure all

connections are tight.

Fuse the input circuit with the recommended super lag

fuses or delay type1 circuit breakers. Choose an input

and grounding wire size according to local or national

codes or use Section A-2. Using fuses or circuit break-

ers smaller than recommended may result in "nui-

sance" tripping from welder inrush currents even if not

welding at high currents.

Unbalanced AC TIG welding draws higher input cur-

rents than those for Stick, DC TIG, or Balanced AC TIG

welding. The welder is designed for these higher input

currents. However, where unbalanced AC TIG welding

above 275 amps is planned, the higher input currents

require larger input wire sizes and fuses per Section A-

OUTPUT CABLES, CONNECTIONS AND

LIMITATIONS

• To avoid being startled by a high frequency

shock, keep the TIG torch and cables in good

condition

• Turn the power switch of the power source OFF

before installing adapters on cable or when con-

necting or disconnecting adapter plugs to power

source.

-----------------------------------------------------------------------

Refer to Figure A.2 for the location of the WORK and

STICK terminals, as well as the TIG Torch connection

panel.

WARNING

A-6

INSTALLATION

PRECISION TIG 375

A-6

TIG TORCH CONNECTION

The Precision TIG torch connection box, located on the

right side of the machine, provides all the input and

output connections for the installation of both air-

cooled and water-cooled TIG torches with fittings con-

forming to Compressed Gas Association (CGA) stan-

dards:

Note: The Precision TIG provides an insulated Torch

Reel and Holster for handy and safe storage of con-

nected torch when not welding, and excess torch cable

length while welding.

Combination connectors (Power/Water and

Power/Gas) are electrically "hot" while welding in

STICK or TIG modes.

If using an Air-Cooled Torch be sure coolant is

shut off and/or Cooler is unplugged from the

Precision TIG Water Cooler Receptacle on the

torch side of the upper case back.

Observe the safety precautions necessary for han-

dling and using compressed gas containers.

Contact your supplier for specifics.

CYLINDER could explode

if damaged.

• Keep cylinder upright and

chained to a support.

• Keep cylinder away from areas

where it could be damaged.

• Never allow the torch to touch the cylinder.

• Keep cylinder away from live electrical cir-

cuits.

• Maximum inlet pressure 150 psi.

-----------------------------------------------------------------

The Precision TIG machines do not have Hi-Freq.

available at the Stick electrode stud, therefore stud

connection adapters (such as LECO. S19257-series)

cannot be used for torch connection.

Single-piece cable air-cooled torches with a 3/8-24 RH

connector fitting (such as the Magnum PTA-9/-17, or LA-

9/-17) require the provided S20403-4 Torch Connector,

while those with a 7/8-14 RH connector fitting (such as

the Magnum PTA-26, or LA-26) require the available

K2166-1 Torch Connector. (See Figure A.3)

Two-piece cable air-cooled torches (such as PTA-, or LA-

torches) can be used with the available K2166-2 1/2”

Stud Connector with with a 7/8-14 LH male fitting.

Magnum PTW-18/-20 (or LW-) water-cooled Torches

require no adapter for Precision TIG connection.

WARNING

WORK

STICK

WORK

STICK

ELECTRODE

STUD

WORK

STUD

TIG TORCH

CONNECTIO

PANEL

FIGURE A

(Shown without hinged stud cover)

REMOTE

CONTROL

RECEPTACLE

CABLE

STRAIN

RELIEF HOLES

FIGURE A.2

A-7

INSTALLATION

PRECISION TIG 375

A-7

AUXILIARY POWER CONNECTIONS

The Precision TIG machines provide a standard NEMA

5-15R duplex receptacle, located on the upper case

back on the torch side of the machine:

• The bottom outlet of this duplex receptacle provides

switched 115VAC power for the Under-Cooler, or

Water Solenoid accessory. This Cooler receptacle

turns on when the arc starts and remains on for about

8 minutes after the arc goes out (with the Fan-As-

Needed machine cooling fan, see Maintenance

Section), so the Cooler’s fan and water pump will not

run continuously in idle, but will run while welding.

• The top outlet of this duplex receptacle provides at

least 8 amps at 115VAC, whenever the Precision TIG

Power switch is ON. This auxiliary circuit is intended

for running 115VAC accessories or small power tools.

Note: Some types of equipment, especially pumps

and large motors, have starting currents which are

significantly higher than their running current. These

higher starting currents may cause the circuit breaker

to open. (See next paragraph)

• Both the receptacle circuits are protected from shorts

and overloads by a 15 amp circuit breaker, located

above the receptacle. if the breaker trips its button

pops out exposing a red ring. When the circuit break-

er cools the button can be reset by pressing it back

in.

Note: When the breaker trips not only will the auxil-

iary and cooler power be interrupted, but so will the

power to the shielding gas solenoid and machine

cooling fan.

The Precision TIG Export models also provide a

grounded 220vac Euro type Schuko receptacle and a

5 amp circuit breaker, located on the upper case back

on the reconnect side of the machine, intended for use

with a 220vac water cooler.

REMOTE CONTROL (If Used)

The Foot Amptrol (included with the Precision TIG

Welding Package), or other Remote accessory, is

installed by routing the plug of its control cable up

through the left cable strain relief hole provided in the

base (see Figure A.2), then connecting the 6-pin plug

to the mating Remote receptacle behind the stud panel

cover. (See Operation Section B-2 for mating plug

wiring.)

Note: If the Precision TIG is equipped with an Under-

Cooler or Under-Storage unit, the Foot Pedal (or other

remote control accessory) and coiled control cable, or

excess cable length, may be conveniently stored in the

drawer while remaining connected.

FIGURE A.3

For Gas Supply hose

with 5/8-18RH male

(Provided with Weld

Package model)

For Coolant Supply

Hoses

with 5/8-18LH male

(Provided with Weld

Package model

Under-Cooler Cart)

1/2-13

Stud

A-8

INSTALLATION

PRECISION TIG 375

A-8

ROBOTIC INTERFACE CONNECTION

Robotic interface can be made at the Remote

Receptacle (See Operation Section B-2). The machine

is shipped with the remote receptacle circuit internally

connected to receptacle J5 of the Control board for

standard Amptrol operation. In order to enable the

remote receptacle for robotic interface its connection

plug must be moved from J5 to J5A on the Control

board. (Refer to the machine Wiring Diagram.)

The robotic interface functions with the Precision TIG

set to either TIG or STICK mode, but must be in

REMOTE switch position for the Preset Control inter-

face to function. When in the REMOTE position with

robotic interface neither the MAXIMUM OUTPUT nor

the MINIMUM OUTPUT panel controls limit the inter-

face control setting over the rated output range of the

machine.

The diagram in Figure A.4 below shows the remote

receptacle plug connections and signals for robotic

interface:

= 70Vdc max.

R = V

/ 5ma

5ma

Robotic

Common

REMOTE RECEPTACLE

(Front View)

For 18-12P Plug

(LECO S12020-27)

ARC START

INPUT FROM ROBOT

(18Vac,10ma switch)

PRESET CONTROL

INPUT FROM ROBOT

(0 -10Vdc = Rated Output Range)

ARC ESTABLISHED

OUTPUT TO ROBOT

(High = Not Welding)

(Low = Welding)

* Precision TIG Control Common.

Note: The Interface connection

cable may pick up noise

interference. Additional

bypass/filtering circuits may be

needed for the external circuits.

FIGURE A.4

B-1

OPERATION

B-1

PRODUCT DESCRIPTION

The Precision TIG 375 is part of a new family of indus-

trial arc welding power sources providing constant cur-

rent, single range square wave AC/DC TIG (GTAW)

with new patented (pending) Micro-Start

Technology,

Presettable Min. and Max. Output controls, and built-in

high frequency stabilization for continuous AC TIG and

DC TIG starting. It also has AC/DC Stick (SMAW)

capability, with adjustable Arc Force availability. A TIG

Pulse Panel, Power Factor Capacitors and a Water

Solenoid are available as field installed optional kits.

Also, a new Undercarriage (with double gas bottle

rack) is available for field installation, as well as a new

Under-Cooler Cart, which is also included in an avail-

able efficiently integrated entire TIG Welding Package

with convenient built-in storage provisions for welding

equipment and components.

The Precision TIG 375 includes advanced features

such as a Digital Meter, Presettable control, Auto

Balance

, Fan As Needed (F.A.N.) fixed Preflow, vari-

able Postflow shielding gas and Timers. In addition, 2-

Step/4-Step and Pulse TIG operation with adjustable

Downslope Time control are included with an available

field installed kit. It also features a Stick stud panel and

a universal TIG torch connection box for simultaneous,

but separated, electrode outputs.

PIPE THAWING

The Precision TIG 375 is not recommended for pipe

thawing.

Duty Cycle

The duty cycle is based upon a 10-minute time period;

i.e., for 40% duty cycle, it is 4 minutes welding and 6

minutes idling. If the rated duty cycle is significantly

exceeded, the thermostatic protection will shut off the

output until the machine cools to a normal operating

temperature. (Refer to Specification Section A-1)

PRECISION TIG 375

ELECTRIC SHOCK can kill.

• Only qualified personnel should

perform this installation.

• Turn the input power OFF at the

disconnect switch or fuse box.

• Do not touch electrically live parts

or electrode with skin or wet cloth-

ing.

•

Insulate yourself from work and

ground.

• Always wear dry insulating gloves.

•

Read and follow “Electric Shock

Warnings” in the Safety section if weld-

ing must be performed under electrical-

ly hazardous conditions such as weld-

ing in wet areas or on or in the work-

piece.

FUMES AND GASES

can be dangerous.

• Keep your head out of fumes.

• Use ventilation or exhaust to

remove fumes from breathing

zone.

WELDING SPARKS

can cause fire or

explosion

• Keep flammable material away.

• Do not weld on containers that

have held combustibles.

ARC RAYS

can burn.

• Wear eye, ear and body

protection.

SAFETY PRECAUTIONS

Read and understand this entire section before operat-

ing the machine.

Observe additional Safety Guidelines detailed in

the beginning of this manual.

WARNING

B-2

OPERATION

B-2

RECOMMENDED PROCESSES AND

EQUIPMENT

RECOMMENDED PROCESSES

The Precision TIG 375 is recommended for the TIG

(GTAW) and Stick (SMAW) welding processes within

its output capacity range of 2 amps DC, or 5 amps AC,

to 420 amps AC/DC. It is compatible with most

Magnum TIG accessories (refer Equipment

Limitations), as well as many industry standard items,

such as TIG torches, hoses, and water coolers.

PROCESS LIMITATIONS

Precision TIG machines are not recommended for arc

gouging due to it's limited output capacity, and are also

not recommended for pipe thawing.

EQUIPMENT LIMITATIONS

The Precision TIG machines are protected from over-

loads beyond the electrical ratings and duty cycles, per

the Specifications Section A-1, A-2, with Thermostat

protection of the primary and secondary transformer

coils.

The Precision TIG machines do not have Hi-Freq.

available at the Stick electrode stud, therefore stud

connection adapters (such as LECO. S19257-series)

cannot be used for torch connection.

PRECISION TIG 375

RECOMMENDED EQUIPMENT/INTERFACE

TIG (water cooled) TIG (air cooled)

Machine: PT375 Welding Package (K1903-1) PT275(K1833-1, -2, K1834-1)

Input Cable/Clamp: User provided User provided

Gas Reg./Hose: (included) LE/Harris 3100211

Magnum Torch: (PTW20 included) PTA9 or PTA17

Magnum Parts: (KP510 and K918-2 included) KP507 or KP508

Work Clamp/Lead: (15 ft. included) K2150-1 Work Lead Assembly

Foot Amptrol: (K870 included) K870 or K870-1

B-3

OPERATION

B-3

1. POWER SWITCH - Input line switch turns input

power ON or OFF, as indicated by the on or off sta-

tus of the front panel displays.

2. POLARITY SWITCH – The 3-position rotary power

switch has detente positions for DC-, AC and DC+

selections for the Electrode output welding polarity.

3. MODE SWITCH – The mode switch allows vertical-

ly positioned selection of the two machine welding

modes. The selected mode is indicated by a lit col-

ored panel light which permits viewing the machine

setting from a distance:

3.a STICK mode (Top position) –Red panel light

ELECTRIC SHOCK can kill.

• When the Power Source is ON in

STICK mode the Electrode circuits of

both the Stick and TIG torch cables

are electrically HOT to Work.

------------------------------------------------------------------------

• The CC Stick mode may be used for general pur-

pose stick welding (SMAW ) within the capacity of

the machine. The capacity is too limited for arc air

carbon (AAC) gouging.

• In this mode; the output terminals are activated

electrically HOT, gas flow is not activated and HOT

START and ARC FORCE levels are fixed, or

Advanced Panel selectable (See Section B-7 ), with

no front panel adjustment.

3.b TIG mode (Bottom position) – No panel light.

• When the Polarity Switch is set to AC, the TIG

mode provides continuous high frequency to stabi-

lize the arc for AC TIG welding.

Hi-Freq. turns on after preflow time with the arc

start switch closure, and turns off when the arc

goes out* after the arc start switch opens.

* Arc voltage and current are sensed to determine if

the arc is established or out.

PRECISION TIG 375

CONTROLS AND SETTINGS

The Front Control Panel contains the knobs and switches necessary for adjusting the operation of the Precision

TIG 375, with function indicator lights and an electronic display for volts and amps. The components are

described below:

FIGURE B.1 - CONTROL PANEL

WARNING

1. POWER SWITCH

2. POLARITY SWITCH

3. MODE SWITCH

4. AC BALANCE CONTROL

5. LOCAL/REMOTE

CURRENT CONTROL

SWITCH

6. MAXIMUM OUTPUT CONTROL

7. MINIMUM OUTPUT CONTROL AND

DISPLAY SWITCH

DIGITAL METER AND DISPLAY

SWITCH

9. POSTFLOW TIME

10. THERMAL SHUTDOWN LIGHT

11. REMOTE RECEPTACLE

12. TRIGGER SWITCH

13. PULSE MODE SWITCH

14. PULSE FREQUENCY CONTROL

15. PULSE % ON TIME CONTROL

16. PULSE BACKGROUND CURRENT

CONTROL

17. DOWNSLOPE TIME

18. HIGH FREQUENCY INTENSITY

CONTROL (NOT SHOWN LOCATION

ONLY)

B-4

OPERATION

B-4

• When the Polarity Switch is set to DC (- or +), the

TIG mode provides high frequency only for starting.

Hi-Freq. turns on after pre-flow time with the arc

start switch closure, and turns off when the arc is

established*

• Also functions for DC+ polarity to permit "balling" of

tungsten for AC TIG welding.

4. AC BALANCE CONTROL – The potentiometer

control permits AC wave balance adjustment from

Max. Penetration (~85% negative wave) with the

control at Max. full CW position, to Max. Cleaning

(~65% positive wave) with the control set near min-

imum CCW position.

• Full minimum CCW position is the Auto Balance

position which is indicated by the Green panel light

turning on. This feature automatically provides the

proper amount of cleaning and penetration for nor-

mal AC TIG welding

• The mid position is the Balanced position (~50%

positive and negative waves).

• The Balance control is only functional if the machine

is set to AC polarity and TIG mode.

5. LOCAL/REMOTE

CURRENT CONTROL SWITCH

– A

2-position switch selects how the welding output is

controlled for both Stick and TIG Modes:

• LOCAL (Top position) selects output control only by

the machine panel Output Control. (See Item 6)

• REMOTE (Bottom position) selects output control to

also be by an Amptrol (See Item 6), or other remote

(10K pot) control connected to the Remote recepta-

cle (See Item 11) This switch selection is indicted by

the Green panel light turning on.

In either position the arc start switch functions when

connected to the Remote receptacle (See Item 11).

6. MAXIMUM OUTPUT CONTROL – The large knob

is used to set the output welding current over the

rated output range of the machine.

• With the Current Control switch to LOCAL position,

this knob sets the welding output level.

* Arc voltage and current are sensed to determine if

the arc is established or out.

• With the Current Control switch to REMOTE posi-

tion, this knob sets the maximum welding level that

the Peak output can be set with the remote Amptrol.

• The new MicroStart

Technology minimum current

circuit provides for low end welding (down to 2

amps) previously unobtainable on an SCR platform

TIG machine.

7. MINIMUM OUTPUT CONTROL AND DISPLAY SWITCH

–

A smaller knob is used to preset the minimum cur-

rent level only for TIG mode. Pressing the Display

(momentary) switch toggle left to Minimum Set posi-

tion displays the Minimum control level setting on the

Digital meter. (See Item 8)

• This knob sets the Start output level. When the arc

lights (using a new built-in TIG start pulse) this level

upslopes quickly (0.5 sec.) and smoothly to the weld

output level. The setting range for this Start control

is the 2 amp minimum range of the machine up to

about 50 amps, but no more than the level set by

the Maximum Output control knob (See Item 6), but

otherwise is independent of the Maximum setting.

• This setting also serves as the Crater-fill level, it can

also be selected (see Section B-7) to be either the

Minimum Output control setting (same as Start set-

ting) as shipped, or the minimum rating of the

machine (2 amps).

• The Remote Amptrol range of control is between

this Minimum setting and the Maximum Output con-

trol knob setting, so these knobs can set the resolu-

tion of the Amptrol. Also, the Minimum setting

serves as both the minimum Amptrol start level

when the arc start switch is closed, as well as the

minimum Amptrol crater-fill level before the arc start

switch is opened to help prevent premature arc out

and Hi-Freq re-initiation.

• In STICK mode the Start control is not functional

since Hot Start level is fixed, or internal Advanced

Panel adjustable (see Section B-7). Pressing the

Display (momentary) switch toggle left to Minimum

Output position displays minimum amps rating of

the machine.

PRECISION TIG 375

B-5

OPERATION

B-5

8. DIGITAL METER AND DISPLAY SWITCH– A3-

digit LED meter is used to monitor the preset and

actual welding procedure based on the Display

(momentary) switch position:

• Before welding with Display switch in center (nor-

mal) position, the digital meter displays the preset

welding amps set by Maximum Output control knob

(See Item 6). If in Stick mode using REMOTE (See

Item 5.), the digital meter displays the preset weld-

ing amps set by the Remote control. (See Item 11)

• While welding with Display switch in center (normal)

position, the digital meter displays the actual weld-

ing amps with one amp resolution (XXX) and accu-

racy within 4%+/-2A of reading.

• Any time in TIG mode and while pressing the

Display switch to left, the digital meter displays the

amps preset by the Minimum Output control knob

(See Item 7).

• Any time in Stick mode and while pressing the

Display switch to left, the digital meter displays the

minimum amps rating of the machine (See Item 7).

• Any time, in either mode, while pressing the Display

switch right to Volts position, the digital meter dis-

plays actual output volts. Volts is displayed with 0.1

volt resolution (XX.X) and accuracy within 3%+/-1V

of reading.

9. POSTFLOW TIME – This knob is used to set the

TIG mode shielding gas postflow time over the

range of about 2 to 60 seconds after the arc is shut

off. The postflow on time status is indicated by the

Green panel light.

• Gas preflow time for TIG mode is fixed at 0.5 sec-

ond, with no panel control.

• Both time ranges are x2 extendable, if needed, by

internal control box selection. (See Section B-7)

10. THERMAL SHUTDOWN LIGHT – This yellow LED

panel light turns on if the machine output is shut-

down because internal overheating has occurred,

and turns off when the thermostat resets.

11. REMOTE RECEPTACLE – A 6-socket receptacle

is provided for the connection of an Amptrol, or

other, remote control: (See Figure B.2)

• When the Current Control Switch, (See Item 5), is

in the REMOTE position the Amptrol, or other

remote (10K pot), connected to the Remote recep-

tacle controls the TIG or Stick mode output within

the range preset by the Maximum and Minimum

Output controls. (See Item 6 and Item 7, also 8 for

meter display)

• When the Current Control Switch is in either LOCAL

or REMOTE positions the arc start switch functions

when connected to the Remote receptacle.

ADVANCED PANEL CONTROLS

The following Advanced Control Panel controls are

standard on the Precision TIG 375 : (Refer to Section

B-10 Tig Weld Cycle Chart for graphic illustration of

these TIG welding functions.)

12. TRIGGER SWITCH – This 2-position switch

selects how the arc start switch ( connected to the

above Remote receptacle) functions; in 2-Step or

4-Step mode:

• DO NOT USE 4-STEP IF USING AN AMPTROL

REMOTE.

• Neither the arc start switch nor the output con-

trol in the amptrol will function normally to shut

off or control the out put. ONLY USE 2-STEP.

------------------------------------------------------------------------

• In 2-Step position the arc start switch functions the

same as without the Advanced Panel:

1. Closing switch starts preflow, then a fixed

(0.5 sec.) ramp time from Minimum (Start)

setting level (See Item 7) to Weld setting.

2. Opening switch initiates Downslope ramp

time setting (See Item 17), from Weld set-

ting to Crater-fill level (See Item 7), which

then stops the arc and initiates Postflow

time (See Item 9).

Note: See Section B-7 for 2-Step operation during

Downslope with Restart feature selected to be dis-

abled, instead of enabled (as shipped).

PRECISION TIG 375

Max

10K ohm

Min

REMOTE RECEPTACLE*

(Front View)

REMOTE OUTPUT

CONTROL

ARC START

SWITCH

*For 18-12P Plug

(LECO S12020-27)

CAUTION

FIGURE B.2

B-6

OPERATION

B-6

• In 4-Step position allows welding without continu-

ously holding the start switch trigger. The arc start

switch functions in the following manner:

1. Closing switch starts preflow, then arc starts

at Minimum (Start) setting level (See Item

7). If the trigger is maintained closed after

preflow time the output remains at the Start

level until it is released.

2. Opening switch initiates fixed (0.5 sec.)

ramp time from Start setting level to Weld

setting.

3. Reclosing switch initiates Downslope ramp

time setting (See item 17) from Weld setting

down to the Crater-fill level (See Item 7) of

the machine.

4. Reopening switch after Downslope time

holds Crater-fill level until switch opens,

then stops the arc and initiates the Postflow

Time (See Item 9). Or, reopening switch

during Downslope time immediately stops

the arc and initiates the Postflow.

Note: See Section B-7 for 4-Step operation during

Downslope with Restart feature selected to be

enabled, instead of disabled (as shipped).

13. PULSE MODE SWITCH – Turns on the Pulse

Mode as indicated by the Green panel light turning

on.

• Pulsing provides a Peak current level set by

REMOTE and/or LOCAL control of the output cur-

rent (See Item5), for a time determined by the Pulse

Frequency Control setting (See Item 14) and the %

ON Time (See Item 15). The balance of the cycle

time is at the Background Current level (See Item

16).

• Pulsing begins after upslope when the output cur-

rent rises above the Background Current level and

ends when the output current drops below this level.

14. PULSE FREQUENCY CONTROL – This knob is

used to set the Pulse Frequency over the peak

pulse range of about 0.1 pps to 20 pps. (One pulse

cycle time = 1/pps = 10 to .05 sec. range.)

15. PULSE % ON TIME CONTROL – This knob con-

trols the duration of the peak current as a percent-

age (5% to 95%) of one pulse cycle. The balance

of the cycle time will be at the Background Current

setting. (See Item 16)

16. PULSE BACKGROUND CURRENT CONTROL –

This knob controls the level of the Background

Current as a percentage (MIN.-100%) of the Peak

(REMOTE and/or LOCAL) output level (See Item

6) down to the Minimum Output setting (See Item

7).

17. DOWNSLOPE TIME– This knob is used to set the

time, over the range of zero to about 10 seconds,

to ramp down from weld setting to Crater-fill level

(See Item 7).

• If the arc goes out after the Downslope time is initi-

ated, the Downslope time is interrupted and the

Postflow time is initiated. This prevents Hi-Freq re-

initiation during ramp down crater fill

• When using an Amptrol remote control, where the

downslope is controlled by the operator down to the

crater-fill level, the Downslope time should be set to

zero so as not to have the Downslope time delay

when the arc start switch is opened.

18.HIGH FREQUENCY INTENSITY CONTROL (NOT

SHOWN)– Allows setting the lowest intensity which

still gives good TIG arc starting with minimized

Radio Frequency Interference (RFI). Control knob

is located on a recessed panel near the easy acces-

sible spark gap side panel. As shipped, the control

is set to minimum.

PRECISION TIG 375

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Lincoln Electric IM703-A User manual

Brand: Lincoln Electric

Model: IM703-A

Category: Welding System

Type: User manual

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PRECISION TIG 375

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Lincoln Electric IM703-A User manual

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Lincoln Electric IM703-A User manual

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